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FreeBSD-SA-14:15.iconv                                      Security Advisory
                                                          The FreeBSD Project

Topic:          iconv(3) NULL pointer dereference and out-of-bounds array access

Category:       core
Module:         libc/iconv
Announced:      2014-06-24
Credits:        Manuel Mausz, Tijl Coosemans
Affects:        FreeBSD 10.0
Corrected:      2014-03-04 12:43:10 UTC (stable/10, 10.0-STABLE)
                2014-06-24 19:05:08 UTC (releng/10.0, 10.0-RELEASE-p6)
CVE Name:       CVE-2014-3951

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

I.   Background

The iconv(3) API allows converting text data from one character set
encoding to another.  Applications first open a converter between two
encodings using iconv_open(3) and then convert text using iconv(3).
HZ is an encoding of the GB2312 character set used for simplified
Chinese characters.  VIQR is an encoding for Vietnamese characters.

II.  Problem Description

A NULL pointer dereference in the initialization code of the HZ module and
an out of bounds array access in the initialization code of the VIQR module
make iconv_open(3) calls involving HZ or VIQR result in an application crash.

III. Impact

Services where an attacker can control the arguments of an iconv_open(3)
call can be caused to crash resulting in a denial-of-service.  For example,
an email encoded in HZ may cause an email delivery service to crash if it
converts emails to a more generic encoding like UTF-8 before applying
filtering rules.

IV.  Workaround

No workaround is available, but systems that do not process untrusted
Chinese or Vietnamese input are not affected by this vulnerability.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.

2) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 10.0]
# fetch http://security.FreeBSD.org/patches/SA-14:15/iconv.patch
# fetch http://security.FreeBSD.org/patches/SA-14:15/iconv.patch.asc
# gpg --verify iconv.patch.asc

b) Apply the patch.  Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

c) Recompile the operating system using buildworld and installworld as
described in <URL:http://www.FreeBSD.org/handbook/makeworld.html>.

Restart all deamons using the library, or reboot the system.

3) To update your vulnerable system via a binary patch:

Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install

VI.  Correction details

The following list contains the correction revision numbers for each
affected branch.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/10/                                                        r262731
releng/10.0/                                                      r267829
- -------------------------------------------------------------------------

To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:

# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base

Or visit the following URL, replacing NNNNNN with the revision number:

<URL:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>

VII. References

<URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3951>

The latest revision of this advisory is available at
<URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-14:15.iconv.asc>
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